Elevator systems



l March 19, 1957 D. SANTINI ETAL ELEvAToR SYSTEMS 'Filed May 4, 1954 8 Sheets-Sheet 1 March 19, 1957 Filed May 4, 1954 I3 B Q e290 B29 Q o o v v o 29A BMO 329A D. SANTINI ET AL ELEVATOR SYSTEMS BMOS L BMGS B299 e158 7 au Bu BRI S70-I s45-4 B45 BN' '1a- Al B45| B553 45-2 D? s45-2 Boo 16 4L 'W 45-3 DO SEA2 I 845-5 BDO \,LBSEA2 33 W4o 3a B33 'y B4 @mn- 1 a-loin o B3B MSK 30o-l 70T I mash] a300-l BTOT PRI-l PRz-n BPm-l Enma-ldjj f sR BSR 62 0D B620?. w SR2 JWSRT BsRa BsRT 'Y #SRS M300 aasna AM8300 YY A 1 /5| I LA ;B5'I BLAI www Imag BMG Q3 L+ A 1:, d! aLAz DL. BzLMEB'YBEL March 19, 1957 D. SANTINI ETAI- ELEVATOR SYSTEMS Filed May 4, 19544 8 Sheets-Sheet 3 EI IIIIJAOINB f mmwIIIIIIIIIIIIIIIIIIII wav mm. WIG/mam Ew I I I I I I I I I I I I I IIIIII I I I I IIIIHMI|I I I I I I I IIIIII..IIIIIII. m|m E i: YMU: u? -m=-.nm H f x IINIxIIxI Il? z I I I I I I III .z y. lllllll III IIIIQ? s IIE xk IIIIIIIIIIIIImIII Fo 1I II I I Co 2N OIIIIIIIIlITIOm? I Illll h :III I I I I :vb un.: un; 2bn msu? wzvI :Il |I I I I I I I5? 52 llll IIIIIIIIIIIIIInv Dz I I I I I I I I I I I I I I lIe I I I I I I I I I I llsov 9 .oleHV N19. MH. o I I I I I I I I I II I I@ o .ma F

IIIIIIIIQIQIII m Nm m m IIII I: ..OOn D man Rm@ mma 23:5 9,2 IIII I Nw u .9|N :I I I I vlvIloYIIlIQw: 5am: n: E.. D n:

JI I, I I I I I I I I I I I I Nw www March 19, 1957 D. SANTINI Erm. 2,785,771

ELEVATOR SYSTEMS Filed May 4, 1954 8 Sheets-Sheet 4 L+ L BTOHT Fig.

March 19, 1957 D. SANTINI ETAL ELEVATOR SYSTEMS 8 Sheets-Sheet 'Filed May 4, 1954 EN IIIIIIIIIIII l I l I l l I En IIIII IK l l l l l |I.||||ll||||*|| a@ l I l l I l I I l I l I I I l l l I .l

5N lllllllllll i i I I l l 5m lllllllllllllllllllll mill w Enola? x Fiqf3A.

mmm llillllllll l|||.|||||l mow `zag man u: u.: o

. l zmom man meu NES 2m@ l fila mam @MSN s 80 1012 63 DE Bao aguja A 'roms March 19, 1957 D. SANTINI ETAL 2,785,771

7 ELEVATOR SYSTEMS Filed May 4, 1954 8 sheets-sheet e 1 wl ES nr e m 7.. er wmllllllll I ,il |||||||||||JwINo|t|mN 2 t l r; .Ww I l NJWO :VJ S ,8

z z..\: zu mzuvo vz E E m EN. P29 9120 m s ollftll om n m A N m 4 m m m |l I l l l l Illovlovf n@ .9 L m m NQ D E wl w l imm mm www www m En TGI En 7 man n 5 4 mmv BIG me 9 v% mom mov 1., 1 n maw unvlmnm 5 w 4v. E, man mman a .w YATE? im M NDv u m M a (#T March 19, 1957 D,SANT|N1 ETAL ELEVATOR SYSTEMS 8 Sheets-Sheet 8 Filed May 4, 1954 zlwz l l I LI m. A M mw 7 .o M M 4 T T niv 4x5 3 7 wm 4 m w D H 2 A I| I A C 5 W N m WMWK T 4 T n m 2 C l A D N O .M AIU. T T m m R I A A N C 5 O m m D m m o n TAL" 4 Fig.5.

nited States Patent O 2,785,771 ELEvA'roR SYSTEMS Danilo Santini, Tenatly, and Arvid M. Nelson, Hillsdale, N. J., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 4, 1954, Serial No. 427 ,475 9 Claims. (Cl. IS7- 29) This invention relates to elevator systems and it has particular relation to elevator systems which are designed for operation without car attendants.

Although aspects of the invention may be employed in elevator systems having car attendants, the invention is particularly desirable for elevator systems of the automatic type which do not have car attendants. For this reason, the invention will be discussed with particular reference to such operatorless systems.

When an elevator car in an operatorless system stops at a landing, such as a floor of a building or structure, it is the practice to hold the elevator car at the oor for a substantial time in order to permit loading and unloading of the elevator car. This time is referred to as a noninterference time. In the prior art systems, the noninterference time may be ot the order of or more seconds for each stop.

in accordance with the invention, the non-interference time is varied in accordance with the requirements for J each of the floors at which a stop is made. To this end, the elevator system is designed to hold an elevator car at a oor at which the elevator stops for a non-interference substantial time, such as 5 seconds.

The non-interference time for a car call may differ from that employed for a lloor call. Thus, if a passenger within the elevator car registers a call for a oor, the elevator car may be held at such iioor for a noninterference time of the order of say three seconds. However, if the elevator car stops in response to a floor call registered oy an intending passenger at one of the intermediate tioors, a longer non-interference time, to allow a passenger to walk to the car that is stopping from the farthest point of the corridor, such as 5 to 7 seconds may be employed.

In one system to which the invention may be applied a substantial non-interference time is provided for each stop of the elevator car. However, upon movement of a passenger into or out of the elevator car, the non-interference time is reset to a smaller value which may be larger for a stop made in response to a iloor call than for a stop made in response to a car call. For example, if the elevator car stops at a oor in response to a car call, the elevator car door opens and remains open for a non-interference time of the order of five seconds if no one leaves or enters the elevator car. However, as soon as a person leaves or enters the elevator car, the non-interference time is reset to a value of the order of one-half second. The non-interference time similarly is reset for a time of the order of one-half second each time a successive passenger leaves or enters the elevator car. If no passenger enters or leaves the elevator car after the predetermined time has elapsed for a period in excess of one-half second, the door starts to close. Once the door starts to close, it may continue to its completely closed position despite the attempt of additional passengers to enter the elevator car or leave the elevator car provided the elevator car is in condition to run. Alternatively, the elevator car door may be conditioned to open each time a passenger attempts to enter or leave the elevator car before the elevator car door completely closes. When this happens, the door does not start to close until one-half second after the beam has been reestablished.

If the elevator car stops in response to a registered oor call at an intermediate door, the elevator car door again is opened and remains open for a substantial non-interference time, such as ve seconds. However, if a person enters or leaves the elevator car, the non-interference time is reset for a smaller value, such as two seconds. lf succeeding persons enter or leave the elevator car at close enough intervals, the non-interference time is reset for each of the persons for a time which may be of the order of one-half second in order to delay the reclosure of the door.

If the elevator car stops at an intermediate floor in response to a registered oor call and is assigned to reverse at such iioor, the door may open for a non-interference time of the order of tive seconds. In this case, entry of a person into the car or departure of a passenger from the car may reset the non-interferenee time to a smaller value of the order of one-half second. Each succeeding person entering or leaving the elevator car within suitable intervals may reset the non-interference time for an interval of the order of one-half second to delay reclosure of the door. Preferably, once the door starts to close, an attempt of a passenger to enter or leave the elevator car will not cause the door to reopen.

In a preferred embodiment of the invention the movement of a passenger or an intending passenger into or out of the elevator car is determined by transmitting energy into the passage traversed by such passenger. Interruption of such energy path by a passenger is ascertained by a suitable detector.

In some cases, a passenger may attempt to prevent the closure of the door for an unreasonably long time by standing in the path of the transmitted energy. In accordance with an aspect of the invention, if the energy is interrupted for an unduly long period, such as four seconds, a closing movement of the door is initiated promptly at the close of such period. Desirably the door may be provided with a protective edge which initiates the stopping or reopening of the door if the door reaches a person located in the closing path of the door. lf as the door reopens the path for the energy is reestablished the door will remain open for the required onehalf second and will not start to reclose as long as the path is interrupted at less than one-half second intervals.

After the movement into or out ot the elevator can` starts, successive loads orpassengers ordinarily follow the first load or passenger rapidly, Each load or passenger after the tirst one resets the non-interference time for an additional small time of the order of one-half second. Consequently, waste time is substantially eliminated and the efficiency of the elevator system is materially improved.

At terminal floors, it may be desirable to control the departure of elevator cars by a suitable dispatcher for the purpose of maintaining adequate spacing of the elevator cars. In such a case, the variable non-interfer ence time is still desirable for the intermediate iioods or landings served by each elevator car. It the car is loading or unloading after a closing operation of the elevator car door is initiated by the dispatcher, the closure of the door may be prevented by operation of the detector.

In a preferred embodiment of the invention, an elevator car is provided with a passage through which load. such as a passenger, may enter and leave the elevator car. The passage may be exposed or closed by a door which is automatically opened as the elevator car reaches a predetermined load transfer position which ordinarily is a landing or floor of a building. Upon expiration ot vthe non-interference time, the door may be closed for the purpose of permitting departure of the elevator car.

A signal or energy is established or transmitted across the passage. A detector is provided which is responsive to a function of the signal or energy. For example, the detector may be responsive to the presence or absence or" radiant energy. If a load, such as a passenger, enters the area through which the radiant energy is projected, the detector senses the presence of such load. The detector, in turn, controls mechanism which, in response to the movement of the load through the passage, resets the non-interference time in the manner previously described. if the detector receives no radiant energy for more than a predetermined time the door may be promptly closed.

Other expedients may be employed for expediting closure of the elevator car door. Thus shortly before the elevator car door is assigned to close, a suitable signal may be operated to warn persons of the impending closure of the door. Such a signal may be in any suitable form such as a lamp or a voice message instructing persons to clear the doorway. A buzzer is quite .suitable for such a signal.

if the elevator car door fails to close within a reasonable time, a second signal desirably is operated. This signal may be of the same general type as the rst signal.

Door speed andv door force may be controlled for the purpose of assuring door closure. lf the elevator car door has remained open for more than a reasonable time, the closing force may be increased for the rst part of the closing movement in order to force from the path of the door any obstruction impeding door closure.

Desirably the door under such circumstances may start its closing movement at a normal speed. However, if the door thereafter' reaches an obstruction in the closing path of the door, the speed of the door may be reduced until the obstruction is removed.

if the closure of the door is prevented for more than a reasonable time, a closing force may be exerted on the door continuously until the door closes. ln a pie ferred embodiment of the invention the closing force is Xerted unless safety edges on both sides of the door opening are operated.

Itis, therefore, an object of the invention to provide an improved elevator system having a minimum of lost time at each elevator car stop.

it is a still further object of the invention to provide a non-interference time for an elevator car which varies in Vaccordance Vwith the nature of the call answered by the elevator car.

It is another object of the invention to provide an elevator system employing protective radiant energy for controlling door closure wherein failure of the radiant energy for a predetermined time terminates the control of door closure by said radiant energy.

Gther objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure l is a schematic View with parts in eleva-tion and parts broken away of an elevator system which may embody the invention;

Fig. 1A is a View in section showing an elevator car employed in Fig. l associated with a hoistway;

Figs. 2, 3 and 4 are schematic views including circuits in straight-line form of a control system embodying the invention;

Fig. is a schematic view including circuits in straightline form of a modified control Vsystem embodying the invention; and

Figs. 2A, 3A, 4A and 5A are key representations of electromagnetic relays and switches employed in the circuits of Figs. 2, 3, 4 and 5. If Figs. 2, 3, 4 and 5 are horizontally aligned respectively with Figs. 2A, 3A, 4A and 5A it will be found that coils and contacts of the switches and relays appearingin the key representations l Vare horizontally aligned with the corresponding coils and contacts shown in these circuits.

Although the invention may be incorporated in an .eie-l vator system employing various numbers of elevator cars serving buildings or structures having various numbers V of floors, the invention can be described adequately with reference to an elevator -system having four elevator cars serving a building having tive floors. The elevator cars may be dispatched from any desired oors. The elevator cars will be assumed to be dispatched between the first floor and the upper terminal or lifth oor.

Because of the complexity of such systems, certain conventions have been adopted. The elevator cars will be identied by the reference characters A, B, C and D. Since the circuits for the cars are similar, substantially complete circuits are shown for the cars A and B. Components associated with the cars C and D are discussed only as required.

Components associated with the elevator cars B, C and D which correspond to a component of the elevator car A are identified bythe same reference character employed for the component of the elevator car A preceded by the letters B, C and D, respectively. For example, the reference characters U, BU, CU and DU designate up switches, respectively, for the elevator cars A, B, C and D. The discussion will be directed primarily to the apparatus and circuits for the elevator car A.

The various relays and switches employed in the circuits may have break or back contacts which are closed when the relay is deenergized and dropped out. The break contacts are open when the relays or switches are energized and picked up.

The relays and switches also may have front or vmaize contacts which are opened when the switches and relays are deenerg-i'zed and dropped out. These contacts are closed when the switches and relays are energized and picked up. ln the drawings the various switches and relays are shown in so far as possible in their deenergized and dropped-out conditions.

Each set of the contacts associated with a relay or switch is identified by the reference character associated withV the relay or switch followed by a numeral identifying the specific set of contacts. Thus, the reference characters Ud, U2 and U3 designate, respectively, the tirst, second and third sets of contacts of the up switch U.

In order to facilitate the presentation of the invention, the apparatus shown in the figures will be brieiy set forth, and the operation of the complete `system thereafter wiil be discussed. The system includes in part the following apparatus:

VAPPARATUS SPEClFlC T0 CAR A V-speed relay U--up switch M-car-running relay D-down switch G*holding relay E-slowdown inductor relay F-'s'topping inductor relay W--uppreference relay X-down-p'r'eference relay WPT- timing relay TT-car-call stopping relay K--ioor-call stopping relay v SG-main starting relay L-car-position relay N-loading relay S-auxih`ary starting relay dil-door relay d-door-control relay DC-door-close solenoid DO-door-open solenoid Sli-detector relay LWA, NU, NUA, 7M-1T, SRT-time delay relays 3tlt-expediter relay I-reversal relay 5, APPARATUS COMMON TO ALL CARS 2DR to SDR- down floor-call storing relays ZUR to 4UR-up floor-call storing relays Figure 1 Fig. 1 illustrates the structural relationships of the elevator cars A, B and associated apparatus with reference to the building structure which. the elevator cars are intended to serve.

The elevator car A and a counterweight 10 are secured to opposite ends of a rope or cable 11 which passes over a sheave 13. The sheave 13 is mounted on the shaft 14 of an elevator driving motor 15. The shaft 14 also carries a brake drum 16 with which a brake 17 or the conventional spring-applied electrically-released type is associated. The motor 15 is secured to the floor 18 of a penthouse located in the structure which the elevator car is intended to serve.

In order to simplify the association of control circuits with the elevator car A, a control device 19 is provided which is operated in accordance with a function of the movement of the elevator car A. In the specic embodiment of Fig. l, the control device takes the form of a iloor selector which includes an insulating panel 20 and a brush carriage 21. A screw 22 is mounted for rotation relative to the panel 20. This screw conveniently may be coupled through suitable gearing to the shaft 14 for rotation in accordance with movement of the elevator car A.

The brush carriage 21 is in threaded engagement with the screw 22. As the elevator car A moves upwardly, the brush carriage 21 is moved upwardly but at a rate much slower than the rate of movement of the elevator car. Similarly, when the elevator car A moves downwardly, the brush carriage 21 also moves downwardly at a slower rate.

The panel 2G carries a plurality of contact segments which are insulated from each other. Thus, the contact segments a2 to a5 are arranged in a row on the panel 20. As the elevator car proceeds upwardly from the basement, a brush 23 mounted on the carriage 21 successively engages the contact segments a2 to a5, as the elevator car approaches respectively the iloors 2 to 5 of the structure. lt will be understood that the Contact segments a2 to a are spaced from each other in accordance with the spacings of the oors. As will be pointed out below, these contact segments are employed with circuits controlling the stopping of the elevator car during up travel in response to car calls.

As a further example, the panel 20 has a single contact segment e1 which is engaged by a brush 24 mounted on the carriage 21 only when the elevator car A is adjacent the rst or `dispatching floor. As will be pointed out below, this contact segment is employed in controlling the operation of a dispatching device.

it will be understood that a number of rows of contact segments and a number of brushes may be employed in the floor selector. However, the foregoing discussion is believed suiiicient .to illustrate the mechanical relationships or" these contact segments and brushes.

Certain apparatus is mounted on or in the elevator car A. Thus, carecall buttons 2c to 4c are provided for registering car calls for the second, third and fourth lloors, respectively.

A slowdown-inductor relay E is provided for the purpose of initiating a slowdown of the elevator car A as it approaches a floor at which it is to stop. The inductor relay may be of conventional construction and includes two sets of break contacts El and E2. When the coil of the inductor relay E is energized, the contacts remain in the positions illustrated in Fig. l until the relay is adjacent an inductor plate located in the hoistway of the elevator car A. For example, when the coil of the inductor relay E is energized and the inductor relay is adjacent the magnetic plate UEP for the second oor, the

magnetic circuit is completed, which results in opening of the break contacts E1. When open, the contacts remain open until the coil of the indlctor relay E is deenergized. The inductor plate UEP is positioned to be reached by the inductor relay E as the elevator car approaches the second floor for the purpose of initiating slowdown of the elevator car. It will be understood that a similar inductor plate is similarly associated with each of the tloors at which the elevator car is required to stop during up travel.

If the coil of the inductor relay E is energized during down travel ot the elevator car, and if the relay reaches the inductor plate DEP for the second iloor, a magnetic circuit is completed which results in opening of the break contacts E2. When opened, the contacts remain open until the coil is deenergized. The inductor plate DEP is so positioned that it initiates slowdown of the elevator car A a suitable distance from the second Floor. A similar inductor plate would be similarly associated with each of the iloors at which the elevator car A is to stop during down travel.

The elevator car A also carries a stopping ind uctor relay F which is similar in construction to the inductor relay E. This relay is employed for initiating a stopping operation of the elevator car A. The stopping inductor relay F cooperates with inductor plates UFP and DEP in a manner which will be clear from the discussion of the cooperation of the slowdown inductor relay with the inductor plates UEP and DEP. lf the coil of the relay F is energized and it the elevator car is to stop at the second iloor while traveling up, when the inductor relay F reaches the inductor plate UFP a magnetic circuit is completed which results in opening of the break contacts F1. This initiates a stopping operation of the elevator car. An inductor plate similar to the plate UFP is similarly associated with each of the floors at which the elevator car A is to stop during up travel thereof. lf the elevator car A during down travel is to stop at the second iloor, the coil of the stopping inductor relay F is energized, and when the inductor relay reaches the inductor plate DFP for the second floor, a magnetic circuit is completed which results in opening of the contacts F2. This initiates a stopping operation of the elevator car A. It will be understood that an inductor plate similar to the inductor plate DFP is similarly associated with each of the iloors at which the elevator A is to stop during down travel thereof.

The elevator car A also carries a mechanical switch 63 which is positioned to be operated by cams 26 located in the hoistway associated with the elevator car. The mechanical switch 63 normally is closed and is opened by a cam 26 when the elevator car A is adjacent the first or dispatching tloor and by a similar cam when the car is at the upper terminal door. lt will be understood that other mechanical switches may be operated in a similar manner by the elevator car A.

An intending passenger on the fourth oor may register a oor call for elevator car service in the up direction by pressing a button of a push-button switch 4U. A similar push-button switch is located at each of the intermediate floors from which an intending passenger may desire to proceed in an up direction.

if .the intending passenger at Vthe fourth door desires to proceed in a down direction, he may press the button of a push-button switch 4D located at the fourth iioor. A similar push-button switch is located at each of the intermediate iioors from which an intending passenger may desire to proceed in a down direction.

The elevator car A is provided with a door DP which is mounted to slide across the passage through which passengers enter and leave the elevator car. The door is moved by means of a lever 28 which is pivotally mounted on the car by means of a pivot 28A. The lever 28 is moved in a clockwise direction about a pivot by means of a door-close solenoid DC for the purpose of closing the passage and is moved in a counterclockwise 7 movement about its passage to open the door by means of a door-open solenoid DO.

When vthe door `is open an object-detecting device is effective. This device preferably includes, a signal or energy which is projected across the passage through which passengers enter and leave the elevator car. This signal may be of any type which can be modified by the movement of a passenger through the passage and in which the modification produced by such movement may he detected. For example, `the signal may be in the form of infrared radiant energy or ultra-violet radiant energy. As a further example, supersonic energy may be projected across the passage. However, it will be assumed that the energy is in the form of visible light which is produced by a lamp LAl mounted on the edge or the door which is the leading edge during a closing movement of the door. The light is in the form of a beam which is focused in any suitable manner ou a suitable detector such as a photocell PCi. The output of the photoceil may be amplified by means of an amplifier Ail/ll which is supplied with electrical energy from a suitable source and the output of the amplifier is applied to a relay PRL The relay PRl may be designed to be picked up as long as the photoceli PCi receives the beam of radiant energy. Detectors of this type are well known in the art. Examples of such detectors may be found in the Kinnard et al. Patent 1,822,152 and in the Ellis, Jr., Patent 1,947,079.

Although a single beam may suce, in some cases it is generally desirable to employ a plurality of beams. Such beams may be produced by interposing suitable reflectors between the lamp LAl and the photocell PC1 to reect a beam across the passage several times before it reaches the photocell. However, for present purposes, it will be assumed that separate lamps and photocells are employed for each of the beams. Thus, in Fig. lA, a second lamp LA2 is provided for projecting energy towards a photoce'll PC2 which is associated with an arnplifier AMZ and a relay PRZ.

In the embodiment thus far described, the lamp LAl is mounted on one edge of the door DP. lf desired, a lamp and a photocell may be placed in any positions wherein the beam between the lamp and photocell is interrupted by the entry of load into the elevator car or the departure of load from the elevator car. Thus the beam may be located between the car and hoistway doors or it may be adjacent the hoistway door. A beam positioned about twelve inches ab ve the oor has been found suitable.

In Fig. 1A, a hoistway door DPH is provided which is coupled to the door DP for movement therewith when the elevator car is stopped atV a door. It will be understood that a separate hoistway door DPH is provided for each of the floors served by the elevator car. The coupling of the two doors may be effected in a conventional manner as by a vane DPV which is secured to the door DP for reception in the slot of a slotted block DPB which is mounted 011 the hoistway door DPH.

The hoistway door DPH is moved to close and expose a hoistwny passage through which load enters and leaves the elevator car. As shown in Fig. 1A, the lamp LA2 is mounted on a hoistway wall or door jamb to protect radiant energy across the hoistway passage towards the photocell PC2 which also is mounted on a hoistway wall. By inspection lof Fig. 1A, it will be observed that the radiant energy transmitted from the lamp LAZ to the photocel'l PC2 is interrupted each time a passenger enters or leaves the elevator car.

r" desired, the edge of the door DP which is the leading edge during a door-closing movement may have an object-sensing device such as a safety-edge SE of conventional type. When such an edge reaches an obstruction, it opens switches SE1, SEZ and SES which may be ernployed in circuits to stop or reopen the door or for other purposes. If center-opening doors are employed, a separate safety edge may be provided for the edge of each door which is a leading edge during closing movement. In the present case, it will be assumed that the second safety edge SEA is located on the elevator car adjacent the photocells PCI, PC2. The safety edge SEA operates switches SEAl and SEA2 for three purposes hereinafter set forth.

The load in the elevator car is weighed in any suitable manner as by the deflection of a spring-mounted platform PL. Loads in excess of say 8() percent of rated capacity open the normally-closed load weighing switch LW, and close a normally-open load weighing switch LWL Figure 2 Fig. 2 shows circuits for the driving motor, the brake, the speed relay V, the up switch U, the down switch D, the car-running relay M, the holding relay G, the slon down inductoi relay E, the stopping inductor relay F, the upapreference relay W, the down-preference relay X, the timing relay T, the door relay the door-control relay 45, the door-close relay DC, the door-open relay DO, the detector relay SR, the time-delay relay SRT and the expediter relay Still. Energy for the various circuits is derived from direct-current buses L+ and L Although various motor control circuits may be employed, it will be assumed that a control circuit of the variable-voltage type is employed. 3y inspection of Fig. 2, it will be noted that the armature SA of the driving motor 15 and the armature 29A of Va direct-current generator 29, together with a series eld winding 23B for the generator, are connected in a series or loop circuit. The lieldwinding 15B for the driving motor l5 is connected directly across the buses L+ and L The magnitude and direction of energization of the driving motor 15 are controlled by the direction and magnitude of the energization of a separately-excited eld winding 29C provided for the generator 25B. lt will be understood that the armature 29A of the generator is rotated at a substantially constant rate by a suitable motor MO which may be a polyphase induction motor energized from a suitable source through a switch MOS. Contacts M051 are illustrated and are operated by the switch to closed position only when the motor MO is conditioned to run. For present purposes, it will be assumed that operation of the switch MOS to closed position also closes the contacts MOSl.

When the elevator car A is conditioned for up travel, the generator eld winding 29C is connected across the buses L+, L through make contacts U2 and U3 of the up switch. `When the elevator car A is conditioned for down travel, the generator field winding isV connected across the buses through the malte contacts D2 and D3 of the down switch. The energizing circuit for the eld winding may include a resistor El which is shunted by make contacts V1 of the speed relay V. By inspection of Fig. 2, it will be observed that the contacts U2, U3, D2 and D3 constitute in effect a reversing switch for controlling the direction of energization of the ield winding. The resistors R1 and the contacts Vl are provided for controlling the magnitude of energization of the eld winding.

The speed relay V may be energized through either of two circuits. One of the circuits includes make contacts U4 of the up switch U, a limit switch Sil which is normally closed and which is opened as the elevator car A nears the upper limit of its travel and the break contacts El of the slowdown inductor relay E. rPhe other circuit is completed through malte contacts Dit of the down switch D, mechanical limit switch 3l which is normally closed and which is opened as the elevator car nears the lower limit of its travel in the down direction, and break contacts E2 of the slowdown inductor relay.

As previously pointed out, the brake i7 normally is spring-biased into engagement with the brake drum i6 and is released by energization of a brake coil 17B. The

coil may be energized either through make contacts U1 of the up switch U or through make contacts D1 of the down switch D.

In order to energize the car-running relay M, certain safety devices 33 must be in their safe conditions. Such safety devices may include switches which are open when the doors of the elevator car and the associated hoistway doors are open, and which are closed when the doors lare closed to control the door relay 40. Such safety `devices are well known in the art. The car-running relay M may be energized through either of two circuits. One of the circuits includes the make contacts 80-1 of the starting relay 80, make contacts W1 of the up-preference relay W, break contacts F1 of the stoppinginductor relay, normally-closed contacts of a mechanical limit switch 34 which are opened when the car nears the upper limit of its travel, and the coil of the up switch U. When energized, the up switch U closes its make contacts U5 to complete a holding circuit around the contacts 80-1 and W1.

The second circuit for energizing the car-running relay M includes the contacts 80-1 of the starting relay, make contacts X1 of the down-preference relay X, break contacts F2 of the inductor stopping relay, normally-closed contacts of a mechanical limit switch 35 which are opened as the elevator car nears the lower limit of its travel in the down direction and the coil of the down switch D. When the down switch D is energized, make contacts DS are closed to provide a holding circuit around the contacts 80-1 and X1.

Before the holding relay G and the inductor relays E and F can be energized, make contacts M1 of the carrunning relay must be closed. In addition, any one set of make contacts J1 of the reversal relay, TT1 of the car-call stopping relay, and K1 of the door-call stopping relay must be energized. A holding circuit around these contacts is established upon closure of the make contacts G1. Energization of the inductor stopping relay F further requires closure of the break contacts V2 of the speed relay.

If the break contacts J2 of the reversal relay are closed, the up-preference relay W is energized only if the elevator car is not operating in the down direction (break contacts D6 are closed); the elevator car is not conditioned for down travel (break contacts X2 are closed); and normallyclosed contacts of a mechanical limit switch 36 are closed. The mechanical limit switch 36 is opened as the elevator car reaches its upper limit of travel. Make contacts M7 of the running relay shunt the contacts J2.

Energization of the down-preference relay X requires closure of the break contacts U6 of the up switch, closure of the break contacts W2 of the up-preference relay, and closure of the normally-closed contacts of a mechanical limit switch 37. The mechanical limit switch 37 is open when the elevator car A is adjacent the rst or dispatching i'loor.

The doors for the elevator car A are controlled by a door-control relay 45. For this relay to be initially energized, the break contacts N1 and TN1 must be closed to indicate that the elevator car is not being loaded at a terminal floor. Break contacts 70HT2 must be closed to indicate that non-interference time allowed for a corridor or oor call has elapsed or the switch 64 must be closed. In addition, the break contacts 70T1 must be closed to indicate that the general non-interference time has expired. The Switch SE1 must be closed to indicate that the safety edge SE of the door is not deected. The make contacts SR1 must be closed to indicate that no object is positioned in the closing path of the door. Finally, the break contacts 70-1 must be closed to indicate that an auxiliary or shortened noninterference time has expired. When the relay 45 picks up, it closes make contacts 45-1 to partially complete a holding circuit for the relay.

If the switch is closed, the energization of the relay 45 is further controlled by two circuits, one containing the switch M081 and contacts 45-4. The remaining circuit contains a cam-operated switch 68 which is open only when the elevator car is at the lower terminal oor, a switch TS1 which is open only when the elevator car is assigned for down peak operation and break contacts NUI of a timing relay.

Should the safety-edge contacts SE1 be held open for an unreasonably long time (a door-hold button could be provided to control the relay 45 in a similar manner) or should the beams of light across the dooway be interrupted'for an unreasonably long time, the break contacts NUAI close to establish with the contacts TNI and N1 an energizing circuit for the relay 45.

The door-control relay 45 controls the energization of the door-close solenoid DC and the door-open solenoid DO. if the contacts 45-2 of the door-control relay are closed, andthe break contacts 40-2 are closed, the solenoid DC is energized. The contacts 40-2 are closed when the door of the elevator car A or an associated hoistway door is away from its closed condition. lf a manual switch 64A is open the energization of the solenoid DC also is controlled by the contacts SE3 and SEA2 in parallel.

if the door-control relay 45 is dropped out, the make contacts 45-3 are closed to complete with the switch 38 an energizing circuit for the door-open solenoid DO. The switch 38 is `a limit switch which is normally closed and which is opened as the door reaches its fully-open position.

The timing relay 70T is connected for energization by make contacts M5 of the car-runninc relay. The energizing circuit is completed through break contacts 360-1 of an expedi ter relay. i t will be noted that a resistor R2 is connected across the timing relay 70T and the contacts 300-1. If the timing relay is energized and the contacts M5 thereafter open, the resistor R2 delays the dropout of the timing relay 70T for a suitable non-interference time, such as 5 seconds. It' the contacts 300-1 open, the relay '7591" drops out promptly.

The detector relay SR is controlled by the make contacts PRI-1 and PE2-1. These contacts are closed respeotively as long as the photocells PCl and PC2 (Fig. l) are illuminated by their respectiveradiant energy beams. The contacts may be bypassed by operation of a manual switch 62.

Break contacts SR2 and SRS of the relay SR respectively control the energization of the time delay relay SRT and the expediter relay Sti. The time delay relay SRT may have a time delay in dropout of the order of one-half second.

The expediter relay 360 also may be energized by closure of contacts Si. These contacts may be arranged to close whenever a car call is registered in the elevator car A for the purpose of expediting departure of the elevator car from a tloor at which it is stopped. For present purposes it will be assumed that the contacts 51 represent a push button which is located in the elevator car A and which is operated to expedite departure of the elevator car from a oor.

Although the lamps LAI and LZ of Fig. l may be continuously illuminated, they are illustrated in Fig. 2 as illuminated through break contacts M6 of the carrunning relay M.

Figure 3 Fig. 3 illustrates additional circuits for controlling door operation and circuits for energizing the car-call stopping relay TT, and the iioor-call stopping relay K.

lf make contacts K2 of the tloor-call stopping relay and the break contacts I3 of the reversal relay are both closed, the timing relay 70HT is energized and picked up. This relay has a Itime delay in dropout determined by a resistor R3 which may be of the order of two seconds to establish a shortened non-interference time under asomar certain conditions. li a d ierent time is desired at a certain lioor a mechanical switch 69 may be operated at such iloor :to modify the dropout time. ln the present case the switch closes to shunt a portion of the timing resistor R3 in order to increase the dropout time .to say three seconds.

Make contacts fiHTl and S Ti lin parallel control the energization of an auxiliary relay 76,

Make contacts SPA control the energization of a tiri ing relay NU. rl`his relay has a time delay in dropout (determined by a resistor R4) which may be of the order of four seconds.

Make contacts SiS of the detector relay SR and the contacts SE?. operated by the safety edge SE control in pant the energization of a timing relay NUA which has a time delay in dropout of say twelve seconds as dctermined by a resistor R5. if the relay NUA is picked up, opening of make contacts LWAL'l drops out the relay promptly.

The timing relay LWA is energized through any of four paths. One path contains the break contacts LW oi the load weighing switch LW. A second path contains break contacts of a switch 68A which is closed only when the elevator car is at the bottom terminal licor and contacts TSS which are closed only during down peak periods. The third path has contacts of a mechanical switch 58B which is closed only when the elevator car is away from the terminal floors and contacts TSi which are closed only during up peak periods. The fourth path contains. a

limit switch which is open only when the door is open.

The car-call push buttons 2c to de normally are biased into their open positions against back contacts x :to flex. Each of the pushbuttons is provided with a holding coil Zee to dce, which is effective for holding the associated pushbutton in its operated condition following a manual operation of such pushbutton. To this end, the pushbuttons may be made oi magnetic material. Such construction ot the pushbuttons is well known in the ant.

Each of the pushbuttons 2c to ic has front contacts controlling the connection of contact segments to the bus L+. When operated, the push `button 2c connects thc Contact segments o2 and i1?. to the bus L+. The push but-tons 3c and 4c .similarly connect contact segments for the third and fourth iioors to the bus L+. inasmuch as the elevator car is assumed to stop at the iiith floor or upper terminal tioor at all times during up travel, the contact segment ne is permanently connected to the bus L+. Similarly, during down' travel, the elevator car A always stops when it reaches the first licor, and the contact segment kl for the rst floor is permanently connected to the bus L+.

it will be understood that the contact segments a2 to a5 are arranged in a row the licor selector 3,9 of Fig. l and are successively engaged by a brush 23 as the elevator car moves from its lower limit to its upper limit of travel. in a similar manner, the contact segments h4 -to lz are arranged in a row in the order of the floors for successive engagement by a brush Mia as the elevator car moves from the upper terminal to its lower limit of travel.

During up travel of the elevator car A, the car-call stopping relay TT is connected between the brush 23 and the bus L- through make contacts W3 or the uppreference relay and make contacts M3 of the car-running relay. Consequently, when the blush Z3 reaches one of the contact segments a2 to a5 which is connected to the bus L+, the car-call stopping relay TT is connected for energization across the buses L+ and L- for the purpose oi stopping the elevator car at the next iioor reached by the car. As the elevator carstops, the brush 23 preferably passes slightly beyond the associated contact segment.

When the elevator car A is conditioned for down travel, the car-call stopping relay TT is connected between the brush 40a and the bus L- through the make contacts 12 X3 of the down-preference relay and the make contacts M3 of the car-running relay. Consequently, when the brush 40a reaches one of the Contact segments h4 to h1 which is connected to the bus L+, the car-call stopping relay TT is energized to initiate a stopping operation of the elevator car at the next floor reached by the car. As the elevator car stops, the brush lila preferably passes slightly beyond the associated Contact segment.

The coils 2cc to icc are connected in series for energization either through make contacts W4 of the up-preference relay or make contacts X4 of the down-preference relay. When the elevator car reverses its direction of travel, the make contacts W4 and X4 both are momentarily opened to deenergize the associated holding coils for the purpose of resetting the car-call push buttons.

Each of the car-call buttons when operated also opens an auxiliary set of normally-closed contacts cx, 30x and 413x respectively. These are employed in a high call circuit which will be discussed below. A set of contacts Scx and a holding coil 5cc also are provided for the ifth licor.

When the down floor-call push button 2D is operated, the down floor-call storing relay 2DR is connected therethrough across the buses L+ and L+ for energization. Upon energization, the relay closes its make contacts ZDRl to establish a holding circuit around the push button. rThe contact segment f2 now is connected (and corresponding Contact segments for the remaining elevator cars are connected) through the contacts 2DR! to the bus L+. The contact segments f4 and f3 similarly are connected to the bus L+ by operation of the down licor-call push-buttons 4D and 3D. The contact segments f4, f3 and f2 for the fourth, third, and second floors are positioned in a row on the iioor selector 19 of Fig. l for successive engagement by a brush S8 as the elevator car A moves from the upper terminal in a down direction.

The floor-call stopping relay K is connected between the bus L+ and the brush 53 through make contacts X5 of the down-preference relay. Consequently, if the elevator car A approaches the second floor during a down trip while a down licor call is registered for such iioor, the engagement of the contact segment f2 by the brush 58 completes an energizing circuit for the iioor-call stopping relay K.

Each of the down floor-call storing relays 4DR, 3DR and 2DR has an operating coil and a cancelling coil, respectively, dDRN, DRN and ZDRN which is energized in opposition to the energization of the operating coil. The cancelling coil ZDRN is connected between a contact segment g2 (and similar contact segments BgZ etc. for the other elevator cars) and the bus L+ through the make contacts ZDR. As the elevator car A reaches the second floor, the following energizing circuit for the cancelling coil is established:

L+, ZDR, ZDRN, g2, 59, X6, M4, L-

Energization of the coil ZDRN opposes energization of the relay by the operating coil and resets the relay. It will be understood that the contact segments g4, g3 and g2 are arranged in a row for successive engagement by the brush 59 as the elevator car proceeds downwardly from the upper terminal tioor to control the energi-zation of the cancelling coils dDRN, SDRN and EDRN.

The down iioor-call storing relays all cooperate with the brushes 53 and 59 in substantially the same manner to control the energization of the iioor-call stopping relay during down travel of the elevator car.

When the up licor-call push button 2U is operated, the up licor-call storing relay ZUR is connected for energization therethrough across the buses L+ and L+. Upon operation, the relay closes its make contacts ZURl to establish a holding circuit around the push button 2U. As a result, a contact segment b2 is connected (and contact segments B112 etc. for the'other elevator cars are connected) to the bus L+ through such make contacts.

13 As the elevator car during up travel approaches the second oor, the brush 60 engages the contact segment b2 to establish the following energizing circuit for the floor-call stopping relay:

L+, 2UR1, b2, 60, W5, K, L-

This conditions the elevator to stop at the second oor. As the elevator car stops at the second floor, a brush 61 engages the contact segment c2 to establish the following circuit for the cancelling coil of the storing relay ZUR:

Such energization of the cancelling coil results in resetting of the storing relay which has its main coil acting in opposition to the cancelling coil. The up oor-call push buttons 3U and 4U similarly control the associated storing relays and Contact segments. lt will be understood that the contact segments c2, c3 and c4, and contact segments b2, b3 and b4 are arranged in rows on the lloor selector for engagement successively by the brushes 61 and 60, as the elevator car A proceeds upwardly.

Figure 4 ln Fig. 4 a starting relay 80, a dispatching device which normally controls the lower terminal dispatching of the elevator cars employed in the system, and a reversal relay I are illustrated.

The starting relay 80 can be energized only if the timing relay 70T is deenergized and dropped out to close its break contacts 70T2. If additional non-interference time is allowed for a corridor or floor call, the manual switch 65 is opened and break contacts 70HT3 of the timing relay also must be closed to permit energization of the relay 80. When the elevator car is positioned at the lower dispatching door, the energizing circuit for the starting relay normally is completed through the make contacts S1 of an auxiliary starting relay. At the upper terminal or dispatching floor, make contacts UTSl may operate in a manner similar to the operation of the contacts S1 for the lower dispatching floor to start the elevator car from the upper terminal floor. Between the dispatching oors, the make contacts S1 are shunted by the contacts of a mechanical switch 63. This switch is cam operated to open when the elevator car is adjacent the upper terminal or dispatching oor and the lower dispatching oor. For all other positions of the elevator car A, the switch 63 is closed.

The selection and timing mechanism include as one component a motor 71 which operates substantially at constant speed. This motor may be of any suitable type, but for present purposes it will be assumed that the motor is a squirrel-cage alternating-current motor which is energized from a suitable source of alternating current. The motor 71 is connected through Ia spring-released electromagnetically-applied clutch 72 to a cam 73 having a protuberance for successively yoperating mechanical switches Y, BY, CY and DY which are associated with the respective elevator cars. The electromagnetic clutch can be energized only if one or more elevator cars are located at the dispatching floor which is assumed to be the rst iloor (one or more of the contacts L1, BLl, CL1, DL1 are closed), and if no elevator car has been selected as the next car to leave the dispatching oor (break contacts N2, BNQ., CN2 and DN2 all are closed).

The motor 71 also may be coupled through a springreleased electromagnetically applied clutch 74 to a cam 75 which is biased towards a predetermined position by a spring 76. The cam 75, when coupled to the motor 71, is rotated against the bias of the spring to close normallyopen contacts 77 a predetermined time after the cam 75 is coupled to the motor 71. The clutch 74 can be electrically energized only if no elevator car is being started (break contacts S2, BSZ, CS2 and DSZ are closed), and if the break contacts 1S1 of the holding relay 1S are closed. The holding relay 1S is energized upon closure 14 .of the contacts 77 to close its make contacts 1S2 for the purpose of establishing a holding circuit around the contacts 77.

The presence of an elevator car at the dispatching oor is determined by the energization of a car-position relay for each of the elevator cars. Thus, a car-position relay L for the elevator car A is energized when `the brush 24 engages the contact segment e1.

The brush 24 is operated by the iloor selector for the elevator car A to engage the contact segment e1 when the elevator car is at the dispatching iloor.

If the elevator car A is at the dispatching tloor (make contacts L2 are closed), if it has been selected as the next car to leave the dispatching floor (switch Y is closed), and if it is not being started (break contacts S3 are closed), the loading relay N for the elevator car A is energized. The loading relay may be employed in'a conventional way to permit loading of the elevator car A. F or example, the loading relay when energized may operate a loading signal, such as a lamp, which indicates that passengers may enter the elevator' car. Conveniently, the loading relay N when energized opens the normally-closed doors of the elevator car A to permit entry of passengers into the elevator car.

After the expiration of a time suicient for cam 75 to close the contacts 77 and energize the relay 1S, the make contacts 1S3 close to complete the following circuit:

L+, L2, s, N3, 1s3, 1.-

The relay S when energized closes its make contacts S4 to establish a holding circuit around the contacts N3 and 1S3, and starts the elevator car A from the dispatching floor.

If the elevator car is loaded before expiration of the interval measured by the relay 1S it may be advisable to expedite departure of the car. To this end a manual switch 99 may be closed to connect the relay 2S for energization through any of four parallel circuits, one for each of the elevator cars. The circuit for the elevator car A includes break contacts 70T3 of the non-interference relay, make contacts N4 of the loading relay and a switch LW1 which is closed only when the load in the elevator car exceeds say 80 percent of rated capacity. Thus if the elevator car A is selected `as the next car to leave the terminal floor (contacts N4 are closed), if the non-interference time has expired (contacts 70T3 are closed) and if the elevator car is fully loaded (switch LWl is closed) the relay 2S picks up and closes its contacts 2S1. Since the contacts 2S1 shunt the contacts 1S3, prior closure of the former contacts expedites dispatch of the elevator car.

Fig. 4 also discloses a reversal relay J which is connected between a brush 66 and the bus L+ through a manually-operated switch 67 and make contacts W7 of the up-preference relay. The brush 66 and an associated row of contact segments k2, k3 and k4 are included in the iloor selector of Fig. l. The contact segments are associated with a call circuit which includes break contacts of the call registering relays and the contacts SCX, 4CX and SCX associated with the car call push buttons. By tracing this circuit in Fig. 4 it will be noted that the bus L+ is connected to the contact segment h2 through the following circuit:

L+, SDRZ, SCX, 4UR2, 4DR2,

4CX, 3UR2, 3DR2, SCX, ZURZ, k2

(A down oor call registering relay is not illustrated in Fig. 3 for the fifth oor, but it will be understood that the break contacts 5DR2 of Fig. 4 are operated by a push button for the fifth floor in the same manner by which break contacts 4DR2 are operated by its push button for the fourth floor.) Consequently, contacts of all call registering relays or car call push buttons which when operated require car travel above the second floor are located between the contact circuit segments k2 for the second lioor and the bus L+.

Operation In order to explain the over-al1 operation of the elevator system, it will be assumed rst that the elevator cars are at the iirst or dispatching floor when the system initially is energized. The cars are conditioned for operation in the up direction. For example, the switches MOS and MOSI are closed and the elevator car A has its up-preference relay W energized. Consequently, make contacts W1, W3, W4, W5, W6, W7 of the relay are closed, whereas break contacts W2 of the relay are open.

The switches 90 (Fig. 2), 63A Fig. 3) and 67 (Fig. 4) are assumed to be open. Since the cars are at the rst floor, the switch 63 also is open. The timing relay 70T is assumed to have timed out. The relays SR, 45 and 4t) are picked up and the elevator car doors are closed; Switches 64A and 68A are closed and switch 68B is open.

The motor 71 (Fig. 4) is energized to rotate at a substantially constant rate.

Inasmuch as the elevator cars are assumed to be at the dispatching floor, the car-position relays I., etc. are energized.

As a result of its energization, the car-position relay L closes its make contacts L2 to prepare certain circuits for'. subsequent energization. ln addition, the make contacts L1 close to complete the following circuit for the clutch 72.

L+, L1, 72, N2, BNZ, CNZ, DNZ, L-

The clutch now couples the motor 71 to the cam '73 for vthe purpose of successively closing and opening the associated mechanicalV switches. It will be assumed that the first switch reached by the cam is the switch Y for the elevator car A. Closure of this switch completes the following energizing circuit for the loading relay of the elevator car A:

L+, L2, N, S3, Y, L

The loading relay N upon energization initiates opening of normally-closed doors of the elevator car A to permit intending passengers on the dispatching oor to enter the elevator car. VVSuch opening is effected by opening of contacts Nl. (Fig. 2) to deenergize the door-control relay 45. This relay opens its contacts 454 and 454. without immediate effect on system operation. However, closure of contacts Aiii-3 energizes the solenoid DO to open the doors. ln opening, the door opens its set of contacts 33 to deenergize the door relay 4S which opens its contacts tti-1 and closes its contacts rtl-2 without immediate effect on system operation. When it reaches open position, the door opens limit switch 3S to deenergize the solenoid DO.

Opening of the break contacts N2 (Eig. 4) deenergizes the clutch 72. Consequently, the cam 73 is un- Vcoupled from the motor 7i. Finally, the 'make contacts N3 close to prepare the starting relay S `for subsequent energization.

When the system `fvas placed in operation, the clutch 74 was energized through the circuit:

As aresnlt of its coupling to the motor HT, the lcam 75 rotates against the bias of its spring 76 until at the expiration of the time interval allowed for loading elevator cars the contacts 77 close. Closure of these contacts completes the following circuit:

L+, is, 77, sz, Bsz, CS2, Dsc, L

Energization of the auxiliary starting relay S closes the make contacts S4 to establish a holding circuit around the contacts N5 and 183. Break contacts S3 open to decnergize the loading relay N. Break contacts S2 open, and this opening causes relay 1S to drop out. This has no immediate eect on the system operation.

The loading lrelay when deenergized opens its make contacts N3 Without immediate effect on the operation of the system. In addition, break contacts N2 close to prepare the clutch 72 for subsequent energization.

The deenergization of the loading relay further closes break contacts Nl (Fig. 2) to complete with the contacts 7&4, SR1, 70Ti and TNl an ene'gizing circuit for the door-control relay 45. The latter relay closes its rnake contacts i5-1 and opens its break contacts 435-3 `without immediate effect on system operation. However, closure of make contacts #t5-2 completes with the contacts dil-12 an energizing circuit for the door-close solenoid DC, and the door now starts to close. If the switch 62 is open and a passenger is in the closing path of the door, he interrupts one of the beams of radiant energy and one of the sets of contacts PR-l or PR2-2 opens to deenergize the detector relay SR. This relay then opens its make contacts SR1 to deenergize the door-control relay 45. The latter opens its contacts iS-2 to deenergize the door-close solenoid and closes its contacts i5-3 to energize the door-open solenoid for the purpose of reopening a partly-closed door. The detector relay also closes its break contacts SR2 and SRS to energize the relays SRT and 399. The energization of the relay 304i has no effect at this time on the operation of the system but the energization of the relay SRT closes make contacts SRTl to pick up the timing relay 71) (Fig. 3). This relay opens its break contacts 70-1. After the passenger clears the door closing path, the detector relay Si?. picks up to close its make contacts SR1, and open its break contacts SR2 and SRS. The :resultant drop out of the relay 306 has no effect at this time on the system operation. However, the opening of contacts SR"a starts a timing out operation of the relay SRT. After the expiration of its time delay, such as one-half second the relay SRT drops out to open its contacts SRT?. and such opening drops out relay 70. The relay 7h closes its t reak contacts F0-l. to complete a circuit for the relay 4S.

The operations of relays NU, NUA and LWA will be discussed below.

ln some cases, it is desirable to prevent a reopening of the door bythe relay SR. In such a case, the manually-operated switch 9i? may be closed to connect make contacts t5-4 of the door-control relay and the switch MOSl around the contacts SR1 and iii-i. When the door-control relay picks up, the resulting closure of its contacts i5- assures door closure despite subsequent drop out `of the relay SR, provided that the switch MGS is closed to indicate that the motor generator set is running. For the following discussion, the switch '53 is considered to be open. Even with the switch 9@ closed, if the door actually encounters a person, the safety edge would open the switch SE1 to deenergize the relay d5 and reopen the door.

lt will be assumed however that no person is in the closing path and that the door closes. Upon closing, the door closes its switch 33 to complete an energizing circuit for the door relay 40 which closes its make contacts 40-1 and opens its break contacts 40-2 to deenergize the door-close solenoid DC.

Turning now to Fig. 4, it will be noted that closure of the make contacts S1 results from energization of the auxiliary starting relay S. Inasmuch as the elevator car A is assumed to have remained at the dispatching door for a time sufficient to permit closure of the break contacts 76T2, an energizing circuit now is complete for the main starting relay 80. Switch 65 is assumed to be closed.

The previously mentioned closure of contacts 40-1 of the door relay (Fig. 2) coupled with closure of the make contacts Sil-1 of the starting relay completes the following circuit for the up switch and the car-running relay:

The energized up switch U closes its make contact U1 to release the brake 17, and 'contacts U2 and U3 close to energize the generator eld winding 29C with proper polarity for up travel of the elevator car. Make contacts U4 close to complete through the limit switch 30 and the contacts E1 an energizing circuit for the speed relay V. The speed relay closes its make contact V1 to shunt the resistor R1 and condition the elevator car A for full speed operation in the up direction. Also, the speed relay opens its break contacts V2 to prevent ener- `gization therethrough of the stopping inductor relay F.

Returning to the up switch U, it will be noted that closure of the make contacts U5 establishes a holding circuit around the contacts 80-1 and W1. Opening of the break contacts U6 prevents energization therethrough of the down preference relay. The elevator car A now is in condition for full speed operation in the up direction and departs from the dispatching floor.

It will be recalled that the car-running relay M was energized with the up switch U. The car-running relay closed its make contacts M1, M3, M4 and M7 (Fig. 3) without immediate effect on the operation of the system. However, closure of the make contacts M2 (Fig. 2) completes with the `contacts 45-1 and N1 a holding circuit for the door-control relay 45. Opening of break contacts M6 deenergizes the lamps LA1 and LAZ. Closure of the make contacts M5 lenergizes the timing relay 70T. This relay opens yits break Icontacts 70T2 (Fig. 4) which causes the starting relay `80 to become deenergized. Openingof break contacts 70T1 (Fig. 2.) does not immediately affect system operation.

It will be assumed now that the passenger in the elevatorcar operates the car-call push button 3c (Fig. 3) Vto register a car `call for the third tloor. Such operation opens the contacts 3cx without immediate effect on the system and connects the contact .segments a3 and h3 to the bus L+. As the elevator car nears the third floor, the brush Y23 Vengages the contact segment a3 to complete the following circuit -for .the car-call stopping relay TT:

L+, 3c, a3, 23, W3, TT, M3, L-

The car-call stopping relay now closes its make contacts TTI (Fig. 2) to energize-the holding relay G and the slowdown inductorrelay E through the closed contacts M1. Energization of the holding relay G completes through the make contacts (G1 a holding circuit around the contacts T1'1.

When the elevator car A in its upward travel reaches the inductor plate UEP (Fig. 1) for the third floor, the break contacts E1 are opened to deenergize the speed relay V (Fig. 2). The speed relay opens its break contacts V1 to introduce the resistor R1 in series with the generator field winding 29C. The resultant reduction in field current slows the elevator car vto a landing speed. in addition, the speed relay V closes'itshreak contacts' V2 to complete through the contacts G1 and M1 an energizing circuitfor the stopping inductor'relayF.

Shortly before the elevator car A in its continued up- Ward movement at the landing speed reaches the third oor, the inductor plate UFP for the third floor is adjacent the stopping inductor relay and completes a magnetic circuit which results in opening of the contacts Fl. Opening of the contacts Fi (Fig. 2) deenergizes the up switch U and the car-running relay M.

The up switch U opens its make contacts U1 to deenergize the brake 17, and the brake is promptly forced against the brake drum 16 by its associated spring. Contacts U2 and open to deenergize the generator field winding 29C. Consequently, the elevator car A stops accurately at the third floor. Opening of the make contacts U4 and U5 and closure of the break contacts U6 have no immediate effect on the operation of the system. As the elevator car comes to a stop the brush 23 may pass the Contact segment for a slight distance to deenergize the relay TT.

The previously-mentioned deenergization of the carrunning relay resulted in opening of the make contacts M1 to deenergize the inductor relays E and F and the holding relay G. The holding relay G opened its make contacts G1 without immediately aifecting the operation of the system.

The car-running relay also opened its make contacts MS to start a timing-out operation of the timing relay 76T. Contacts M5 preferably open with a slight time `delay to assure prior closure of contacts 390-1. This relay T has a time delay in drop out sufficient to permit discharge of passengers or entry of passengers into the elevator car A. For example, a time delay of five seconds may be employed. Opening of the make contacts M3 and closure of the break contacts M4 have no immediate eifect on the operation of the system. Closure of contacts M6 illuminates the lamps LAI and LAZ, vand these illuminate their associated photocells to close contacts FRI-ll and PE2-1 which pick up relay SR. The pick up of relay SR and the resulting deenergization of relays SRT and 309 have no immediate effect on the operation. However, the relay SRT starts to time out.

Opening of make contacts M2 deenergizes the door control relay i5 and this relay opens its make contacts 45-1 and t5-2 without immediate effect on system operations. However, closure of break contacts 45-3 completes with the switch 38 a circuit for the door-open solenoid DO and the door now opens. In opening, the door opens its switch 33 to deenergize the door relay 40 without immediate etiect on system operation.

Let it be assumed that instead of a car call, an up oor call was registered for the third floor by operation of the push button 3U (Fig. 3). Such operation energizes the up floor call storing relay SUR which closes its make contacts 3` El to establish a holding circuit around the push button. The contacts 3UR1 also serve to connect the contacts segment b3 and corresponding Contact segments for the remaining elevator cars of the system tothe bus L+. Opening of contacts 3UR2 and 3UR3 does not affect the operation of the system at this time.

As the elevator car approaches the third floor, the brush 66 engages the Contact segment b3 to energize the oorcall stopping relay K through the following circuit:

Upon energization, the floor call stopping relay closes its make contacts vKl (Fig. 2) to energize through the contacts M the holding relay G, the slowdown inductor relay E and the stopping inductor relay These relays operate in the same manner previously discussed to stop the elevator car accurately at the third iioor. Contacts K2 of the floor call stopping relay lalso close to cornplete with the contacts i3 an energizing Vcircuit for the relay 76H?. The latter relay 73E-1T closes its make contacts '7M-YY1 and opens 1reak contacts 'I'HTZ and 76H23 Without immediately affecting the operation of the system.

As the elevator car A slows down to stop at the third oor, the brush 61 engages the contact segment c3 to complete the following cancelling circuit:

L+, 3UR1, SURN, c3, 61, W6, M4, L-

It will be recalled that the break contacts M4 close as the elevator car stops at the third oor. As a result of its energization, the cancelling coil SURN resets'the up floor-call storing relay for the third oor. Such reset is accompanied by deenergization of the floor-call stopping relay K which opens its make contacts K1 with out affecting system operation. However, the opening of the make contacts K2 starts a timing out operation of the relay 70HT.

Referring toFig. 4, it will be recalled that the mechanical switch 63 is open only at the dispatching-floor and the upper-terminal floor positions of the elevator car. Since the elevator car is now at the third door, the switch 63 is closed. Consequently, as soon as the timing relay 70T drops ont, the break contacts NT2 close to complete an energizing circuit forV the starting relay Si). This operates in the manner previously discussed to start the elevator car upwardly. In this way, the elevator car A continues to the upper terminal floor, answering all registered car calls and all registered up oor calls during its upward trip.

As previously pointed out, the drop out of the timing relay 70T provides a non-interference time which may be of the order of 5 seconds. If desired, a longer noninterference time may be provided for a stop made in response to a corridor or floor stop. For example, assume that the switches 64 (Fig. 2) and 65 (Fig. 4) are open and that the relay 76H1" has a delay in drop out of say six seconds. Under such circumstances, the relay 45 (Fig. 2) cannot be energized to close the door and the relay 80 (Fig. 3) cannot be energized to permit starting of the car until a Vnon-interference time of six seconds has elapsed to permit closure of contacts 70HT2 and 79HT3. It will be assumed, however, that the switches 64 and 65 are closed.

If a passenger leaves the elevator car at the third iloor promptly, say, in 1 second, it follows that a substantial and unnecessary delay in the departure of the elevator car would be imposed vif the relay '70T is allowed to complete its normal timing interval before the car departs from the third door.

In the present case, the departure of the elevator car is expedited to an extent dependent on whether the elevator car is answering a car call or a oor call. By reference to Fig. 1, it will be noted that when the car stops for acar call and the passenger leaves the elevator car at the third door, he temporarily interrupts the beams of lradiant energy directed towards the photocells PCI and PC2. Such temporary interruption temporarily inter rupts and drops out the relays PRI and PRZ.

Referring to Fig. l and Fig. 2, it Will be noted that the drop out of the relays RRl and vPRZ opensV make contacts PRll-FL and PRE-1' to deenergize the detector relay SR. The detector relay opens its make contacts SR1 to prevent energization therethrough of the door-control relay 45 as long as the passenger stands in the closing path of the door. in addition, break contacts SR2 and SRS close to energize the time delay relay SRT and the expediter relayA 30). Energization of the time delay relay SRT results in closing of the make contacts SRT and pick up of the relay 7G without immediately atecting the operation of the system. The relay 70 opens its break contacts 70-. The expediter relay 300 opens its break contacts S-1 to instantly drop out the timing relay 70T. Since the timing relay is now dropped out, it closes its break contacts 70761. However, since the contacts SR1 and 70-1 are open, the door-control relay 45 cannot be energized. ln addition, break contacts 70T2 (Fig. 4) close to complete with the switch 63 an energizing circuit for the main starting relay 80. The

efr-saith main starting relay closes its make contacts t-l (Fig. 2) without immediate effect on the operation of the system. Contacts SR4 and SRS (Fig. 3) open to start timing out operations of the relays NU and NUA.

It will be assumed that the passenger passes promptly through the doorway and that the beams of radiant energy are promptly reapplied to their associated photocells. As a result of such reapplication, the make contacts PR- and PRZ-l reclose to energize the detector relay SR. This relay opens its break contacts SR3 to deenergize the expediter relay 300, but such deenergization has no immediate effect on the operation of the system. Opening of the break contacts SR2. initiates a timing out operation of the time delay relay SRT. Closure of the make contacts SR1 has no immediate effect on the energization of the door control relay V45 for the reason that the contacts 70-1 arev still open. Closure of make contacts SR4 and SR5 (Fig. 3) reenergizes the relays NU and NUA.

Upon the expiration or" the one-half second time delay in dropout of the relay SRT, this relay drops out to open its make contacts SRTl, the auxiliary relay 7() now closes its break contacts 76-1 to complete the energizing circuit for the door-control relay 4S. This relay 45 thereupon operates in the manner previously described to initiate la door-closing operation of the door of the elevator car A and the starting of the elevator car A from the third oor. It should be noted that this operation may save several seconds of time in starting the elevator car from the third tloor.

Should another passenger immediately follow the tirst passenger to leave the elevator car at the third Hoor, the radiant energy beams again would be interrupted to deenergize the detector relay SR. This relay would reclose its break contacts SR2 to reenergize the time delay relay SRT. Since the relay SRT has not yet dropped out, the reenergization thereof occurs before the elevator car door starts'to close and delays reclosure of the door for the full time delay of the relay SRT.V If a larger number of passengers follow each other out of the elevator car A, it follows that the relay SRT is reset in response to each departure of a passenger. A similar operation results from-the successive entry of a plurality of passengers into the elevator car. Following the entry of the last passenger,VY the relay 45 is operated to close the door and start the elevator car.

Thereiect'of movement of a passenger or an intending passenger out of or into the elevator car located at the third door now will be considered for the case in which the elevator car has stopped at Vthe third iloor in respouse to the tlooi Vcall registered by operation of the push button 3U. lt'will be recalled that if the elevator car A stopped at the third iloor under these conditions, the'make contacts K2 (Fig. 3)A closed to energize the timing relay 70HT and then reopened to startl a timing out operation of the relay. For this sequence, this relay may have a delay in,drop out of the order of two seconds. When the relay 70HT was energized, it closed itscontacts ftlHTl to assist in maintaining energized the auxiliaryrelay 70. It is assumed that the switch 6ft 'is closed to shunt the break contacts NHTZ.

If no passenger enters or leavesrthe elevator car for a period of two seconds, the timing relayY 'itil-IT finally drops out,V to deenerg'me the auxiliary relay '74). The relay 74)closes its. bre/ak contacts 70-1 (Fig. 2) but the door control relay Vv45 cannot yet be energized for the reason that thebreak contacts '70T1 of the timing relay '76T' are still open. i f

lf the elevator car remains at the third door for a total of tive Vseconds without the entry of an intending passenger or departure of a passenger from within the elevator car, the timingl relay 76T Ydrops out to close its break contacts 70T1 and'70T2 (Figflt). This operation of the timing relay initiates the closing of the door and the startingof they elevator car from the third o'o'r in the manner previously' described.

Next let it be assumed that :t passenger left the elevator car one second after the elevator car stopped at the third oor. It will be recalled that at this time the timing relays 70T and 70HT both are picked up and both are timing out. A 4As the passenger passes through the doorway he temporarily interrupts the beams of radiant energy directed toward the photocells PC1 and PC2. Consequently, the relays PRI and PR?. temporarily drop out to interrupt monientarilythe energizing circuit for the detector relay SR;- The detector relay SR momentarily opens its make contacts SR1 without immediate effect on Vthe operation ofI =the system. InY addition, break contacts SR2 and SRS close to energize the time delay rela* SRT and the expediter relay 30G. Opening ofthe make contacts SRA and SRS starts timing out operations of the relays NU and NUA.

As a result of its drop out, the expedite. relay 366 opens its break contacts Soil-1 to drop out instantly the timing relay 76T. The resulting closure of the reak contacts 'tTi is ineffective for energizing door control relay 45 for the reason that the break contacts '7G-t of the auxiliary-relay 7d are still open. The closure of the break contacts 7ti`l`2 (Fig. 4) completes an energizing circuit for the main starting relay 80. However, the main starting relay can not start the elevator` car until the door is closed.

The temporary energization of the time delay relay SRT results in an energizing and timing out of this relay, inasmuch as this relay is assumed to have a delay in drop out of the order of one-half seconr. lt iinally drops out to open make contacts SRTI. Such opening has no eect on the system for the reason that the make contacts 70H11?. are still closed.

Upo'n the expiration of two seconds following the stopping of the elevator car at the third floor, the timing relay liT drops out to open its mare contacts ItlHTL This deenergizes the auxiliary relay i9 and results in closure of the break contacts 70-l to cjmplete the following circuit:

The door control relay 45 is now energized to initiate a closing operation of the door and the resultant starting of the elevator car by a sequence which will be clear from the foregoing discussion. y

Let it be assumed next that just before the timing reay IGI-IT timed outa second passenger followed the first passenger out of the elevator car. This resulted in another temporary interruption of the beams of radiant energy directed towards the photocells and PC2 and a temporary `drop out of the relays PRl and ViRZ. Consequently, the detector relay SR again is temporarily dropped out to open its make contacts SRE momentarily and close its break contacts SR3 momentarily to energize the reiay 3%. Such operations have no immediate effect on the performance of this system. The temporary opening or" the make contactsSRfi and SRS starts timing out operation of me relays NU and NUL and then reenergizes the relays.

it will be noted that the relaySR also temporarily energizes the time 4delay relay SRT and this relay closes its make contacts SRT just before the make contacts 'lilHTi open. Consequently, even though the `time period for the timing relay 76H1 has expired, the make coutac SRTi maintain the energization of the auxiliary elay 76 for approximately a half second to permit movement of other passengers through the doorway as required. It will be recalled that the door cannot be reclosed until the auxiliary relay 7l) drops out to close its break contacts "704i, 'From 'the discussion, it should be clear that as long as successive passengers follow cach other into or out of the elevator car within one-half second intervals,

the door of the elevator car remains open to permit such movement of the passengers. One-half second after the departure of the last passenger, the contacts SRTl open to drop out the auxiliary clay 70 and permit closure of the elevator car door.

la order to make the relay NU effective for controlling the operation of the system, the manual switch may 'oe closed. Such closure connects the break contacts NUl of the timing relay NU and contacts of a switch TS1 across the contacts SR1 :and 70-1.

a passenger attempts to delay closure of the elevator car door by standing in the path of the beams of radiant energy directed towards photocells PCI and PC2, he also maintains open the make contacts SR4 to permit a timing out operation of the timing relay NU. Upon the .non or' its time delay, which may be of the order o1 tout seconds, this relay closes its break contacts to complete with the switch TS1 or the switch 68 an energizing circuit for the door controlled relay 45. Under these circumstances, the door promptly starts to close. lf the door is provided with a safety edge and the safety edge encounters the passenger, the switch SE1 opens and initiates a reopening operation of door. Should the passenger move out of the path of the beams while the door is reopening, the detector relay SR again picks up and closes its make contacts SR4 to energize the timing relay NU. This relay opens its break contacts NU1 to prevent energization therethrough of the door control relay. In addition, make contacts SR1 close and break contacts and SRS open. Opening of the contacts SR2 initiates `a timing out operation of the relay SRT. Une-half second later this relay drops out to open its make contacts SRT! and deenergize the auxiliary relay '70. The auxiliary reiay then closes its break contacts 79.14 to complete an energizing circuit for the door contror relay 45 and this initiates a closing operation of the door.

It may be desirable under certain conditions to prevent the timing relay NU from controlling the closure of the elevator car door. Thus, contacts may be included which render incttective the contacts NUI of the timing relay. For example, it may be undesirable to permit such control by the timing relay NU during a down-peak period `at the lower terminal lioor. The switch TS1 may be designed to open during the down-peak period. VIt will be understood that during a down-peak period the demand for elevator service is predominantly in the `down direction.

For present purposes, it wili be assumed that the switch TS1 is a time switch which opens its contacts during certain periods of the day when down-peak travel is expected. If the time switch is to be effective only at the lower terminal lloc-r, it may be shunted by the mechanical switch 68 which is cam operated to open only at the lower terminal iloor and which is closed for all other positions of the elevator car.

Let it be assumed next that the safety edge SE is operated to hold the contacts SEZ open for a period in excess of the dropout time delay of the relay NUA or that a person stands in the paths of the light beams to maintain the contacts SRS open for such a period. Under such circumstances the relay NUA drops out and closes its contacts NUA to complete with the contacts TNI and Nl an energizing circuit for the door control relay 45, to linitiate a positive door-closing operation. If deired the dropout of the relay may operate contacts for controlling the door-closing motor or solenoid to close the doors at slower than normal speed and with increased force. Such oper-ation of the `door will be discussed bclow. if the safety edge SE is released or the person moves out of the paths of the light beams before the door closes, the relay NUA is reenergized and opens its contacts to restore the vdoor control relay 45 to control by the safety edge SE and the light beams. However, 'if such restoration is not desired the vrelay NUA may be 23. given siiircient delay in pickup to assure closure of the door.

Even though contacts NUAI are closed, if the switch 64A is open the closure of the door is prevented if both safety edges SE and SEA are operated. Under such circumstances the parallel contacts SE3 and SEAZ are both opened to deenergize the door-close solenoid DC. If either of the safety edges thereafter is released the door resumes its closing movement.

Under some circumstances the eiiciency of the elevator service may be improved by expediting the dropout of the relay NUA. Such dropout is expedited by opening of the make contacts LWAl of the time-delay relay LWA.

The time delay relay LWA may have a time delay in dropout of the order of three seconds. if the elevator' car is not fully loaded the relay LWA is energized through the load switch LW. lf the elevator car is loaded in excess of say 80% of capacity, the load switch LW opens to permit deenergization of the relay LWA. If desired the relay LWA may have an instantaneous drop out when deenergized.

Preferably the deenergization of the relay LWA is prevented while the elevator is at predetermined floors under predetermined traffic conditions. Thus if the elevator car is at the lower terminal floor the switch 68A is closed. I-f the elevator system at the same time is conditioned to provide down peak service the switch TS3 is closed. Since the relay LWA is maintained energized through the switches 68A and TSS the relay is ineffective for shortening the dropout time delay of the relay NUA.

I-f the elevator car is away from both terminal floors the switch 68B is closed. If the elevator system is conditioned at the same time to provide up peak service the switch T54 is closed. Under these conditions energization of the relay LWA is maintained through the switches 68B and TS4, and the relay is ineffective for shortening the dropout time delay of the relay NUA. During an up peak traffic is predominantly in the up direction.

Systems for providing specialized elevator service during peak periods are known in the art. For present purposes it will be assumed that a time switch closes contacts TS4 during the periods of a day for which up peaks are expected to occur. Y Y

Thus if the elevator car is fully loaded at any door during periods other than up and down peak periods,

or if the elevator car is fully loaded at any door other 1 than the lower terminal oor during a down peak period or if the elevator car is fully loaded at a terminal oor lower terminal floor.

Next let it be assumed that the switch e7 in Fig. 4 is closed to permit assignment of the elevator car A under certain conditions to reverse at an intermediate landing. The conditions may be such that no down oor call or no car call is registered for a door above such landing and that no up oor call is registered for such landing or for any higher landing while the elevator car is set for up travel andV is approaching such landing.

For illustrative purposes, let it be assumed that the elevatorV car A is approaching the fourth iioor and that a down iloor call for the fourth floor constitutes the only call registered in the system. Under such circumstances, the down floor call registering relay 4DR is picked up and the break contacts 4DR2 (Fig. 4) are open by a sequence clear from the foregoing discussion.

As the elevator car nears the vfourth door, the brush rilhe relay I closes its make contacts J1 (Fig. 2) to complete with the make contacts M1, an energizing circuit 4for the relays E, F and G. These operate in the manner previously described to stop the elevator car at the fourth floor. In addition, break contacts J2 open. As the elevator car stops at the fourth oor, the make contacts M'7A` of the runnin" relay also open to deenergize the up-pref erence relay W. Since the `11p-preference relay closes its break contacts W2 to energize the down-preference relay X, the elevator car now is assigned for down travel.

Finally, the reversal relay I opens its break contacts J3 to prevent energization therethrough of the timing relay )aus complete the foi- Y 7C-HT. ri`he door call stopping relay resets and opens its y floor for `a maximum of iive seconds.

make contacts K2 slightly before contacts J3 reclose. Consequently, the relay '70HT is ineective for controlling the non-interference time.

The non-interference time of the elevator car now is controlled solely by the 4timing relays 76T and SRT. Consequently, the elevator car remains at the fourth However, if a passenger leaves the elevator' car or enters the elevator car within the five second period lthe non-interference time is reset to have a value of only one-half second. This operation of the relays 76T and SRT will be understood from the foregoing discussion.

if the additional time provided by the timing relay 76H2? is desired for all floor calls the contacts J3 may =be shunted by a manual switch 69A. The contacts M4 may then be given a slight time delay in closing. Under `these circumstances the brush S3 is positioned to engage `the contact segment f4 when the elevator car stops at the vfourth door. Closure of the contacts X5 when the elevator car is set for down travel energizes the relay K and the relay K is then -deenergized by reset of the registering relay tDR following closure of the contacts M4. The momentary closing of the contacts K2 ope-rates in the manner previously described to provide a minimum noninterference time of two seconds. However, it will be assumed that the switch 69A is open and that a reversal of the car at an intermediate floor provides a minimum non-interference time of one-half second.

As the elevator car A` on its up trip approaches the upper terminal or fifth floor, the brush 23 (Fig. 2) engages the contact segment a5 to complete the following energizing circuit for the car-call stopping relay:

L+, a5, 23, W3, TT, M3, L-

The car-cali stopping relay operates in the manner previously discussed to stop the elevator car accurately at the upper-terminal iloor.

As the elevator car A reaches the upper-terminal oor, the mechanical switch 63 (Fig. 4) opens. Consequently, the elevator car A cannot star-t from the upper-terminal floor until it is started by its upper-terminal dispatching device represented by the contacts UTS. it will be understood that the upper-terminal dispatching device may be similar to the dispatching device discussed for the first door. For present purposes it will be assumed that the contacts UTSl operate for the upper-terminal dispatching floor in the same manner by which the contacts Sl operate for the lower dispatching floor.

As the elevator car reaches the fifth floor, the limit switch 36 (Fig. 2) opens to deenergize the 11p-preference relay W. This relay opens its make contacts W1, W3, W5, W6, without immediately aiecting the operation of the'system. VHowever, opening of the make contacts W4 deenergizes the holding coils for the Vcar-call push buttons, and these are reset. In addition, closing of the break contacts W2 completes the following energizing circuit for the down-preference relay:

c+, U6, W2, x, 37, as, L- 

